1. Field of the Invention
This invention relates to a dehumidifying machine for dehydrating materials, more particularly to a dehumidifying machine which can dehydrate effectively materials and which has a filter device mounted therein so as to prevent the materials from being polluted.
2. Description of the Related Art
Referring to FIG. 1, a conventional dehumidifying machine includes a tank 11 which is used to receive some materials, an induced draft fan 13 which is mounted on the top side of the tank 11, an annular separating plate 12 which extends downward from the central section of the top surface of the tank 11 so as to divide the tank 11 into an outside portion 113 and an inside portion 112, and a heating device 10 disposed in the inside portion 112 of the tank 11. The induced draft fan 13 has two inlet portions 131 which are communicated with the outside portion 113 of the tank 11, and an outlet portion 132 which is communicated with the inside portion 112 of the tank 11. The separating plate 12 has a plurality of holes 121 formed therein so as to allow air to move through the separating plate 12. The tank 11 has two filter plates 111, each of which is positioned between the interengaging surfaces of the outside portion 113 and the inlet portion 111.
When the dehumidifying machine is actuated, air can be moved from the outlet portion 132 of the induced draft fan 13 into the inside portion 112 of the tank 11 so that the air can be heated by the heating device 10. At this time, the heated air can move through the holes 121 of the separating plate 12 into the outside portion 113 of the tank 11 so as to heat the materials in the outside portion 113 of the tank 11, thereby dehydrating the materials. In addition, when the air is exhausted from the inlet portions 131 of the induced draft fan 13, the filter plates 111 can block the impurities carried in the air from moving into the induced draft fan 13.
The drawbacks of this conventional dehumidifying machine are as follows:
1. Because the distances between the heating device 10 and the vertically spaced portions of the separating plate 12 are different, the heated air moving through the holes 121 at the lower and upper portions of the separating plate 12 has different temperatures. Accordingly, the materials in the outside portion 113 of the tank 11 cannot be dehydrated evenly.
2. Some tiny impurities, such as dyestuffs and the like, mixed with the materials may move through the holes 121 and coat on the heating device 10 and thus be burned to produce smoke which may stain the materials.
3. When some impurities carried in the air are deposited on the filter plates 111, it is quite difficult to clean the filter plates 111 by taking off the top cover of the tank 11.